THE widow of ex-spy Alexander Litvinenko hides her anguish behind shades as she bids him a final farewell yesterday.

Grieving Marina, 44, tenderly clasped her hand to her chest in the rain as she was joined by 50 mourners at the solemn ceremony.

The funeral came amid news that a Russian who met the former spy on the day his food was spiked was in a coma with radiation poisoning.

And seven workers at the London hotel where they held talks have tested positive for deadly polonium 210, it also emerged.

Mr Litvinenko, 43, was buried at Highgate Cemetery in North London - where the father of Communism, Karl Marx lies. The former agent is believed to have converted to Islam on his deathbed and a Muslim imam said a graveside prayer - against the wishes of Marina.

But her husband's dad Walter said earlier this week that he had asked to be buried according to Muslim rites. A memorial service at Regent's Park mosque was held before the funeral.

Walter, accompanied by the ex-spy's brother Maxim, gave a 10-minute tribute at the cemetery.

Marina and son Anatole, 12, were joined by Mr Litvinenko's mum Nina Belyavskaya and first wife Natalia. Some of his closest friends - including Russian billionaire Boris Berezovsky and Chechen dissident Akhmed Zakayev - were on hand to console the family as the oak coffin was lowered into the ground at 2.30pm.

Another friend, Alex Goldfarb, called the occasion "a very emotional moment for me and for everybody who was here". He added: "I hope those who did this will face justice."

The coffin did not have to be lead-lined because of the polonium 210 - contrary to earlier claims.

But Mr Goldfarb said the Health Protection Agency had advised against cremation. He said: "Officials told the family that had they wanted to cremate him, they would have had to wait 22 years for the radioactive material to decay."

The probe into the ex-KGB man's death took another twist yesterday with reports that Dmitri Kovtun - who saw him on November 1 - lay critically ill in a Moscow hospital. He and fellow Russian Andrei Lugovoi met Mr Litvinenko at the Millennium Hotel on the day he also saw an associate at a nearby Itsu sushi bar.

Although staff at the hotel have been found with low levels of polonium 210, Itsu staff have got the all-clear - making it more likely Mr Litvinenko was poisoned at the Millennium.

A Russian state-owned news agency claimed Mr Kovtun fell into a coma after being quizzed by Russian investigators and Scotland Yard on Wednesday. The agency said: "By the doctors' diagnosis, Kovtun's condition is critical." Local prosecutors confirmed he "developed an illness also connected with the radioactive substance".

They have launched their own probe into Mr Litvinenko's death and may send detectives to Britain to investigate.

But Mr Lugovoi's lawyer Andrei Romashov said one of Mr Kovtun's representatives denied he was in a coma. He added: "His health is no different from when he was questioned."

Mr Kovtun's movements across London partly match the radiation trail. He and Mr Lugovoi arrived in the capital on October 16 on a jet later found contaminated with polonium 210. They stayed at the Sheraton Park Lane hotel, which has also tested positive, and other jets they used to return to Britain have radioactive traces.

The Health Protection Agency insisted the contaminated Millennium Hotel staff were in no imminent danger.

A spokeswoman said: "There is no health risk in the short-term and in the long-term the risk is judged to be very small."

Prof Mario Scaramella, who lunched with Mr Litvinenko at Itsu, was discharged from hospital on Wednesday after doctors found he had no symptoms of poisoning.